A double-effect heat-pump machine comprises two coupled heatpump circuits. Input heat is supplied to a first generator which works in a first, high pressure range and delivers working fluid vapor to a first condensator where the working fluid vapor is condensed and heat of condensation is generated. The heat of condensation is coupled to a second generator, which works in a second, intermediate pressure range and delivers working fluid vapor to a second condenser also working in said intermediate pressure range. The machine further comprises an evaporator and an absorber working in a third, low pressure range. The evaporator takes up heat of evaporation and, thus, effects cooling. Relatively low-grade heat is produced in the second condenser and in the absorber and must be disposed off as waste heat.
Double-effect machines are well known in the art and described e.g. in German Auslegeschrift DE-AS No. 1,501,141, U.S. Pat. No. 3,837,174, German Offenlegungsschrift DE-OS No. 29 44 960 and in my European patent application No. 82102473.4 (publication No. 0061721A1) corresponding to my U.S. patent application Ser. No. 417,118 filed under PCT No. 09/02/82 and incorporated by reference.
In the following, the term "exchange unit" is defined as in my above-identified earlier application and denotes the main components of a heat-pump cycle, in which the thermodynamic state of a working fluid may be changed, as by supply or removal of heat and/or by absorption in or desorption from an absorbent, as well known in the art. Thus, the term "exchange unit" includes generator, condenser, evaporator or desorber, absorber or resorber units which comprise main components of absorption cycle machines as well known in the art.
Generally, the heat-pump or thermodynamic cycles of the machines described in the above references are both heat coupled and fluid coupled, i.e. the working fluid circuits of the various stages communicate with each other.
U.S. Pat. No. 3,483,710 discloses a refrigerator system of the absorption type comprising two cascaded thermodynamic cycles which are thermally coupled but have individual, not-communicating working fluid circuits. Permanent heat transfer means are provided to transfer heat of condensation from an absorber in a first, higher loop to a generator in a second, lower loop, and heat of absorption from an absorber in the second, lower loop to an evaporator in the first, higher loop.
FIG. 9 of my earlier application discloses a heat-pump comprising three pairs of exchange units operating in upper, medium and lower pressure ranges, respectively. Heat transfer is provided for between a generator, operating in the upper pressure range, to a first exchange unit operating in the medium pressure range and in a relatively high temperature range, or alternatively between an absorber operating in said lower pressure range, and a second exchange unit operating in said medium pressure range and a relatively low temperature range compared with said relatively high temperature range. Thus, said first and second exchange units can alternatively operate as second generator and condenser respectively or as second absorber and evaporator, respectively.
FIG. 43a of my above-identified earlier application Ser. No. 417,118 shows schematically a three-stage heat-pump system which comprises four pairs of exchange units. Each pair operates in a different pressure range, thus, this proposed machine employs four pressure ranges. A first condenser operates in a first, upper pressure range and receives WF vapor from a first generator operating in the same pressure range. Heat of condensation produced in the first condenser is transferred to a second generator operating in a second, next lower pressure range to energize this second generator. Further, heat generated in an absorber operating in fourth, most lowest pressure range is transferred to an evaporator operating in a third second lowest pressure range.